I like how the eye has lots of dark and light lines in it, it adds to the realistic feel. To make it more realistic, try getting a darker shade of blue and making small lines around the pupil.

If the white parts are light, they aren't supposed to blend into the eye, they are supposed to be kind of like light in anime eyes, the only difference is that in realistic art I don't think the light goes over the pupil.

I also like how I can see a little bit of a dark blue circle around the eye, you should make it a few shades darker so it is more apparent. ^^